A metamaterial is a new artificial material that emerges in the past decade and generates a modulation effect on an electromagnetic wave. Basic principles of the metamaterial are to design a microstructure (or called an artificial “atom”) of a material artificially, and grant specific electromagnetic characteristics to such a microstructure. In this way, a material made of a massive number of microstructures may macroscopically have an electromagnetic function desired by people. Different from a conventional material technology in which a way of using electromagnetism is developed according to natural properties of an existing material in the nature, a metamaterial technology designs properties of a material artificially and makes a material as required. A metamaterial generally lets a specific number of artificial microstructures be attached to a substrate that is somewhat mechanical and electromagnetic. Such microstructures of a specific pattern and a specific material generate a modulation effect on an electromagnetic wave that passes through the microstructures and has a specific band.
Conventional metamaterials, for example, an American patent “METAMATERIAL GRADIENT INDEX LENS” whose disclosure number is “U.S. Pat. No. 7,570,432B1”, an American patent “BROADBAND METAMATERIAL APPARATUS, METHODS, SYSTEMS, AND COMPUTER READABLE MEDIA” whose disclosure number is “US2010/0225562A1”, are generated by attaching microstructures onto a substrate of a panel. In preparing a panel metamaterial, a processing process of attaching microstructures onto a substrate is relatively simple, and a processing process applied in a conventional PCB board field may be used, for example, etching, diamond etching, ion etching, and electroetching. A panel-shaped metamaterial has merits of miniaturization and thinness, but it restricts an application scope of the metamaterial.
Responsivity of a conventional metamaterial to an electromagnetic wave is largely decided by microstructures. However, when the metamaterial needs to respond to some electromagnetic waves that have a relative wide span of an electromagnetic parameter range to implement specific functions, for example, when a wave-transmissive effect is required for all electromagnetic waves with incident angle from 0 to 90°, or when polarization conversion needs to be implemented for all electromagnetic waves with polarization angle from 0 to 90°, because the responsivity of the microstructures to electromagnetic waves has a limit value, it is rather difficult or even impracticable to obtain a desired metamaterial by using a conventional metamaterial design method, for example, by emulating a specific microstructure and changing its topological structure or dimensions or the like.
When the metamaterial needs to be made into a curved surface, the processing process of microstructures of the curved surface is difficult and precision is not high. For example, difficulty of preparation becomes very high when a processing process in a conventional PCB board field is applied. For example, an existing European patent whose application number is “EP0575848A2” discloses a method for processing a metal microstructure on a three-dimensional curved surface, and its detailed implementation manner is: etching microstructures one by one by means of exposure and imaging performed with a laser sensor. In such a manner, both processing costs and craft precision control costs are high, which makes it impracticable to implement fast and massive production.